There are two principal routes for the commercial production of ethanol. One procedure is based on petrochemical technology. Starting with ethylene, ethanol is produced by means of the catalytic hydration of this olefin.
The second method for ethanol synthesis relies on the fermentation of sugar, derived either from corn or sugar cane. A major drawback to fermentation processes is the fluctuation in the cost of commodities used as raw materials.
Propanol, or more specifically n-propyl alcohol, is manufactured by the oxo process. In this operation, ethylene is reacted with carbon monoxide and hydrogen to give propanal. This aldehyde is then reduced with hydrogen, resulting in the product, propanol.
The oxo process is also used to produce butanol. In this case, propylene is treated with carbon monoxide and hydrogen in the presence of a catalyst to give butyraldehyde. This intermediate is then reduced to produce isobutyl alcohol as well as some n-butyl alcohol.
Alternatively, butanol can be produced by fermentation. Increased attention is being paid to this technology because of the interest in renewable materials.